Exchange 2007, OWA 2007 and "Service Unavailable" after new software installation


So Howard emails me yesterday about a problem he’s been trying to figure out. His Outlook Web Access 2007 on the Exchange 2007 installation suddenly stopped working. Nothing changed 🙂

There are many reasons why Outlook Web Access 2007 will give you the “Service Unavailable” error message, mostly because the mail/public databases are not running, something you will be able to quickly determine from the Event Viewer. However, this one was slightly different. This event viewer generated the following error message, with event code 2268:

Event ID: 2268
Raw Event ID : 2268
Record Nr. : 3746
Source: W3SVC-WP
Category: None
Type : Error
Machine : ACISERVER2
Could not load all ISAPI filters for site/service. Therefore startup aborted.

Event ID: 2274
Raw Event ID : 2274
Record Nr. : 3745
Source: W3SVC-WP
Category: None
Type : Error
Machine : ACISERVER2
ISAPI Filter ‘C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_filter.dll’ could not be loaded due to a configuration problem. The current configuration only supports loading images built for a AMD64 processor architecture. The data field contains the error number. To learn more about this issue, including how to troubleshooting this kind of processor architecture mismatch error, see

Confirm it, restart IIS and you will see the following error:


Basically, you (or the software you were installing) switched your IIS site where OWA is installed into either a 32bit mode or ASP.NET 1.1. Since Exchange 2007 Outlook Web Access 2007 only runs on ASP.NET 2.0 in 64bit mode, you need to fix it back.

First, disable the 32bit mode for your web site. By default OWA goes into the Default Web Site context (0) so the following will take care of that:

cscript C:\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 0

Second, register ASP.NET 2.0 as the default framework for that web site:

aspnet_regiis.exe -i
Start installing ASP.NET (2.0.50727).
Finished installing ASP.NET (2.0.50727)

Restart IIS and you should be all set.

Remember, you have to be careful with third party software deployments and IIS on the 64bit platform. Before you do your rollouts create the web site for it, put it in its own worker group. If you allow it to do its own deployment it will usually go into the Default Web Site, DefaultAppPool and you’ll be reading this blog post again. Also remember that just because the software says it’s 64bit it doesn’t mean all the components of it (like web control panels) are 64bit as well.

In this case, it was Symantec AV that did it.

Also, I write technical articles on weekends so that Damian Leibaschoff can score a few hours of overtime. Time to give brother a raise…

29 Responses to Exchange 2007, OWA 2007 and "Service Unavailable" after new software installation

  1. Damian says:

    Let’s hope that in SBS 2008 the risk of this happening is diminished since we run OWA from our own web site (SBS Web Applications ).

    And yes, it is almost 12:00am CT on Sunday 🙂


  2. vlad says:

    Stick it on a timesheet Bubba 🙂


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  4. Dan McCoy says:

    Funny, I just ran into this same problem last week. I installed Quickbook 2006 on my server so I could run in multiuser mode. Quickbooks installed .net 1.1. It’s Server 2K3 R2 x64 and exchange 2007. The next morning, I was out on a job and tried to logon and had the same darn problem. After I figured out the same problem… my solution… restore the metabase.xml file. Problem solved!

    Worst part about this is that this very same thing bit me 8 months ago… and I forgot and went and did it again! ARggh..

  5. I had the same problem again. The client called at 9:30 PM.. Checked the logs, no apparant issues. So I went and did the fix anyway. Problem went away. So the question that I had is why the logs were not showing the problem. I finally found the answer.. the problem had occured at 5:10 AM; 16 hours earlier! It was easy to find the log entry when I knew what event to look for. OWA had not worked all day, but they did not complain. If the client had complained earlier in the day, I might have found the log entry earlier. That is why I did not find the log entry the first time, I did not go back in the logs far enough. Live and learn..

  6. macthorough says:

    C:\WINDOWS\Microsoft.NET\Framework64\v2.0.50727\aspnet_regiis.exe -i

    I had to take out the > character and put in a \

  7. Derek says:

    At least Trend Micro’s setup actually warned of the problem and says “It’s recomended to install on another server”.. which is halarious.. I guess they couldn’t just write the damn thing to install into it’s own isolated app pool… Sometimes it scares me to know people like that write software for my bank…

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  9. Sun Kwok says:

    Thanks! Same thing happened to me this morning and this really helped!

  10. Chiranjeev says:

    Hey Mazek,

    Thanks a ton for valuable solution. It works and actually solve my problem.
    Thanks alot.

  11. joe says:

    Your awesome! Thanks. Worked like a charm.

  12. T says:

    I got hit by this from Symantec AV too!
    (And if you installed Endpoint Manager and are getting c5 stop errors, guess where they’re coming from?)

    In my case, owa/activesync went down, the c5 reset caused the broadcom drivers to reset their static IP to dynamic, uninstalling Symantec broke vmware server’s virtual cards, preventing use of some servers… I really hope this is the last of the issues. To quote someone from the symantec support forums “This unstable mess will leave your server in tatters. Get rid of it before you lose your job.”

  13. Alex says:

    Hi Vlad,
    I’m thanksfull for your online resourse!
    Your article “Exchange 2007, OWA 2007 and “Service Unavailable” after new software installation”
    was my life saver, at 3 am we were lost and clueless. Microsoft were recomending completely different solution and guess what…. it didnt work.
    Thank you so much for sharing such valuable experince.
    BTW tis problem affecting not only OWA.
    Active Sync gets affected as well.

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  15. Dave says:

    Thank you.
    This worked perfectly!!!

    I had a fresh install of Exch2007 with a new cert, so I had a lot of variables and it never worked from the first time I checked it.

    Thank you Vlad.

  16. Another Alex says:

    Hmmm…I followed your steps and was able to get OWA from a 503 to a 404. Guess I’ll keep googling until I get it down to a 200. Thanks for this part of it, though.

  17. Another Alex says:

    Ok, in case anyone else ends up with a 404 after doing this, go into IIS Manager’s Web Service Extensions list and allow ASP.NET v. 2.0.50727. Thanks again for this article.

  18. JP says:

    Thnkas very much. Installed Trendmicro on a 64 bit server and it killed all the websites. This worked great.


  19. JP says:

    Thanks very much. Installed Trendmicro on a 64 bit server and it killed all the websites. This worked great.


  20. This blog Is very informative , I am really pleased to post my comment on this blog . It helped me with ocean of knowledge so I really belive you will do much better in the future . Good job web master .

  21. Abhishek says:

    Hi Bro,

    You are right. You do deserve a raise. As you are aware today is the last day of the year and I was upgrading the exchange server to 2007 at my office. Everything went alright but this error kept on bugging me. After following your steps, it work so would like to thank you. Keep doing the good work.

    Have a happy new year!!

  22. Paula says:

    Thanks for helping out. I installed Blackberry Server Software on our Exchange Server and kept getting Service Unavailable Error. This worked like a charm.

  23. Shlomo A says:

    GREAT HELP – Thanks

  24. Ross says:

    Thank you very much. This worked like a charm. One of our admins tried to install BES on the Exchange 2007 server and it broke OWA and Outlook Anywhere.

  25. Martin says:

    Same problem, but mine happened after installing Symantec Endpoint Protection Manager + SMSFME. I tried this post, among others, and NONE are working. Everything IIS related shows (service unavailable). I have uninstalled/re-installed IIS 6.0 and STILL have the problem. Symantec is offering no support because OWA/IIS is not their product. I have a single server, 2003 Standard x64 w/ SP2, Exchange 2007 SP1 x64, etc. OWA was working fine before the install (90% of my users use OWA), and now it is not working. I even uninstalled SEP + SMSFME and the problem will not go away. I think the next step will be to re-install .net, but i dont want to create more issues.
    Anyone have any idea?

  26. Roger Siow says:

    Thanks mate! Your solution work like a Gem! 🙂

  27. shirc real says:

    That worked like a charm, in my case someone installed vmserver on my exchange box. You are a life saver saved me alot of time, now I can leave early for the weekend. Thanks again!

  28. chad says:

    this information is pretty much exactly the same as this microsoft help article:

    thanks for helping me, it got me looking in the right place

  29. Lynn Smith says:

    Thank you very much.I find good tips for the Exchange 2007, OWA 2007.

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